Power hammer



G. E. HIEBER POWER HAMMERv Filed March 2O 1925 Aug. 30, 1927.

ATTOR EY OJ v Patented Aug. 30,v 1927.

PATENT OFFICE.

GEORGE E. HIEBER, GNN1`Q'AT,O-IO, ASSIGNOR TO CONCRETE SURFACING MACHINERY 1CO1V|IPANY,'O]5l (.INGINNA'lI,A OHIO, -A COB'ORATION 0F OHIO. 'i

rownn 'HAMMER Application led vMarch 20,1925. Serial No. 16,962. y

This invention relates to that type of manually manipulated power hammers which are operated by means ofleXible rotating shafts, and its object is [to provide a portable structure of this character wherein the blows-of the hammer are'cushioned by means of a, body oflair .confined within a reciprocating cylinder and the force which pulls the hammer back from lthe chisel or other tool upony which it is operating is alsoY exerted through a cushion of air.. y

AIn the accompanying drawing, Fig. 1 is avertical section of this improved hammer on the line '1 1 offFig.. 2. Figs. 2, 3 and 4 are sections on the lines 2-2, A3--3 and 44-4 respectively of Fig. 1. p

Similar reference letters refer to like parts throughout the several views. l

The body 1 of this hammer isformed with a handle 2 of any desired character by which it can be lpositioned relative `to the work. lts opposite end 3 is tubular to receive the reciprocating cylinder 4', and its end is closed by means of the plug 5 .which serves as a guide for the tool A.

rThe c Tlinder 4 is fitted with a head 5 having a central hole to receive 'the stem (ir lof the piston 7. r his stem risformed withr a small groove 8 to' permit the passage of air into the outer end of the cylinder. The end of this stein is adapted to Contact wit-h the inner end of the tool A, which is slidable in theplug 5.

A vertical shaft 11, mounted in the rear end of the body 1 and in theclosure plate l12, carries a pinion 13, and its lower end may be drilled at 14 andta'pped 'toi receive the end of a connector 15 which attaches `to any desirable iiexible shaft 16 by means of which this device may be driven.

The main crank comprises the disks 17 and 18, united by a. crank pin "19, preferably formed on 'one of the `disks and-extending through afhole in vthe other. VShafts 21 and 22 are formed integral with the disks `l'and 18 respectively and bushings 23 and 24 constitute bearings therefor; the former being mounted 'in the body 1 and the latter in the closure 12. The disk 18 is formed with teeth to mesh with the teeth of thev pinion 13.

lThe crank pin 19 extends through the eye 25 at the inner end of the connecting rod 26.

The cylinder 4 is formed to receive the bushings 27 in which the pin 28 is mounted and this pin extends through and is non-rotatable inthe eye 29 at the outerend of the connecting' rod 26. This pin may be hollow if desired.

'As shown in Figs. 1, Sand 4,l the cylinder 4 and the bushings 27 are formed with air passages y31 and the pin 28 is formed with ports 32 which aline lwith the passages 31 when the 4crank pin is about midway of its backward stroke. That is, these ports are out of alinement while the cylinder 4 is moving outward, or to the left inl Figsf l and 2, and during the beginning and during the ending of the inner movement of the cylinder. Atvthe inner and outer ends of these movements the ports and passages are as shown in Fig.,4, that is, the passages to t-he interior of' the'cylinder 4are' closed. The crank shafts are supposed to turn clock-wise inthe drawings.

The operation is as follows VVhen the ports 32 and passages Blare alinedat the middle of the backstroke of the crank, air

may rush into the cylinder 4, permitting the hammer? to 'lag and slide to the outer end. of the cylinder 4.

Thesmail groove 8 permits the air at the front end of the cylinder tov escape very slowly so that the 'hammer is cushioned at the front endv of the cylinders. lVhen therefore the crank reaches the` rear end of its stroke, the hammer 7' will be at the outer end of the cylinder and the space at the inner endy of the cylinder will be filled with air which is compressed to some extent by the hammer as the cylinder moves outward. l,

This air cannot .escape as ythe ports 32 and passages` are no longer in alinement. The result is that when the stem 6 strikes the -tool A, Athe blow is cushioned by theair-in the innerend of the lcylinder and the impact of the `hainmej 7 on the tool is alive7 and'is similarto the blow delivered by the pistons ofthe well known pneumatic v'ham'- mers.' I r y 1 1 This air cushion notV only secures the very desirable live77 blows ofthe hammer but itV also relieves theactuating parts ofthe 'very destructive shocks which would be received if this hammer 7 were rigid with the cyl-- inder 4. This therefore insures long life to this tool.,

If no leakage occurred, this tool could be assembled with the desired amount of airv within the rear end of the c linder 4, but as this air is liable to leak out, provide means 1. n a power hammer, the combination of a body, a cylinder slidable therein, va crankshaft lmounted in said body, a connectingr rod extending therefrom to the cylinder to more the cylinder inwardly and outwardly, a pistoirhammer in said cylinder, a pin connecting the cylinder to the connecting rod, said pin and cylinder being formed with air passages which aline while the cylinder is making the middle portion of its inward stroke and are out of alinement during the remainder of the time to cause the piston hammer to be cushioned during the outward movement of the cylinder.

2ln a power hammer,the combination of a body, a cylinder slidable therein, a crankshaft mounted in said body, a connecting rod extending therefrom to move the cylinder inwardly and outwardly, a pistonhammer in said cylinder, said cylinder being formed with passage to admit outside air to its inner end, and'means controlled by said connecting rod to open said passage during the inward stroke of the cylinder and to close it vduring the outward stroke, said air serving to cushion the piston-hammer during said outward stroke.

In a tool of the class described, the combination of a body, a cylinder slidable therein, a crank shaft mounted in said body, a connecting rod extending from the crank shaft to said cylinder, a pin connecting the connecting rod and cylinder, said cylinder having an air passage adapted to admit outside air to its inner end, said pin extending across the passage and provided with an air port adapted to aline with said passage at a predetermined point of its inward strokes, said port and passage being' out of alinement during the outward stroke of the piston, Aa piston-hammer in said cylinder, and having Aa stem extending from the cylinder in the opposite direction to said pin, an annular closure for the end of the cylinder fron'rwhich the stem extends, said hammer being cushioned by the air within the ends of the cylinder.l

shaft to said cylinder,` a pin connect-ing the connecting rod and cylinder, saidvcylinder having an air passage extending to its inte- Y rior, said pin extending across the passage `and provided with an air port adapted to aline with said passage at a predetermined point ofl its stroke, a piston-hammer in said 'Y cylinder, and having a stem extending from the cylinder in the opposite-direction to said pin, an annular' closure for the end vof the cylinder from which the stem extends, said hammer being cushioned by the air within the ends ofthe cylinder the Vair beingad'- mitted to one end through said'air portand passage, said vstem having a longitudinal groove to admit air to the other'end ofthe cylinder.

5.1n a tool of the class described, the combination of body and a crank revoluble therein, alcrank pin on the crank, a connect ing rod mounted on the pin, a hollow mem-V ber slidable in said body and operatively connected to said rod, and a hammer mounted in said hollow'member, the parts being formed with air passages connecting to the outside vair to secure air cushions for said hammer within the hollow body, the passage to the inner endof the cylinderl being opened, and closed by said connectingrod.

6. ln a power hammer, the combination of a body, a cylinder slidable therein, a crankshaft mounted in said body, a connecty wardly from the cylinder, and said-cylinder having an annular closure for theouter end of the cylinder vand through which said stem extends, the groove in the stem permitting a restricted ,fiowof air into and out of the outer end of the cylinder at all times.

GEORGE n mensa. 

